Electrical contact apparatus

ABSTRACT

Electrical contact apparatus for high voltage circuit breakers and the like includes a pair of conical rollers mounted on a shaft and held under spring compression against a pair of conducting pins which are movable with respect to each other, upon the energization of the breaker. Each conical roller has a peripheral groove formed therein, the radius of the groove being less than the radius of either pin. The wedges of the grooves engage the surfaces of the pins to make an electrical connection therewith.

O United States Patent r1 1 [11] 3,790,732 Slamecka et al. [45] F b, 5, 1974 [54] ELECTRICAL CONTACT APPARATUS 2,273,245 2/ 1942 Ander 200/166 BB inventors: Ernst slamecka; Hans p y; 3,564,168 2/1971 Blgg 200/166 BB Egon Zemann, all f B li FOREIGN PATENTS OR APPLICATIONS Germany 633,520 7/1936 Germany 200 166 BB Assignee: Siemens Akfiengeseuscha, 1,167,946 4/1964 Germany 200/166 BB Munchen Germany Primary ExaminerRobert K. Schaefer [22] Filed: Aug. 10, 1972 Assistant ExaminerWilliarn J. Smith [21] pp NO: 279,383 Attorney, Agent, or Firm-Hugh A. Chapm [57] ABSTRACT g Application Priority Data Electrical contact apparatus for high voltage circuit Aug. 12, 1971 Germany 2141138 breakers and the like includes a pair of conical rollers mounted on a shaft and held under spring compres- [52] US. Cl 200/166 BB, 200/166 BH sion against a pair of conducting pins which are mov- [51] Int. Cl. H0lh 1/06 able with respect to each other, upon the energization [58] Field of Search. 200/166 BB, 166 BE, 166 BF, of the breaker. Each conical roller has a peripheral 200/166 BH, 166 D groove formed therein, the radius of the groove being less than the radius of either pin. The wedges of the [56] References Cited grooves engage the surfaces of the pins to make an UNTTED AT S PATENTS electrical connection therewith. 3,024,334 3/1962 Rhodes ZOO/166 BB 8 Claims, 3 Drawing Figures O 160'8 16b 16b I :l i1 27 10' 1 I 26 23K 25 "5 1 Y 1 I ll 2 1' II 1 10 I i; l I ll l 15a 15a 5 15b 15b ELECTRICAL CONTACT APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to electrical contact apparatus incorporating conical rollers for making electrical connection between two conducting members which are movable with respect to each other.

2. Description of the Prior Art Known electrical contact apparatus includes a conical contact roller, which is pressed by a spring against two parallel electrical conducting rods which are movable relative to each other. A representative example of such apparatus is described below in detail with reference to FIG. 1. So that the known conical contact roller can transmit large currents, three pairs of contact rollers, displaced by 120, are arranged in a plane transversely to the contact rods. In addition, similar contact devices are stacked on top of each other with a separate cage in several planes. However, such known apparatus requires a considerable expenditure of space and material.

- SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a simpler and less expensive electrical contact apparatus, which incorporates conical contact rollers having increased current-carrying capacity.

In accordance with the present invention, electrical contact apparatus comprises a parallel pair of electrical conducting rods capable of undergoing relative movement with respect to each other. The apparatus additionally includes at least one roller means having first and second portions for making electrical contact with each of said rods. The apparatus further includes spring loaded means for positively holding the roller means against the rods.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows, for purposes of comparison with apparatus constructed in accordance with the invention, prior art electrical contact apparatus, incorporated for example in high voltage circuit breakers;

FIG. 2 shows one embodiment of electrical contact apparatus constructed in accordance with the present invention,

FIG. 3 shows another embodiment of electrical contact apparatus constructed in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The objects of the present invention are achieved by providing multiple lines of electrical contact between the conducting rods of a circuit breaker and the rollers in engagement therewith. In respect of the modification necessary for known conical rollers, multiple lines of electrical contact are obtained by adding a relief or groove in the surface of the cone. Each edge of the groove is in electrical contact with each conducting rod, thus doubling the number of contact points as compared with prior art apparatus. The desired increase in the currentcarrying capacity is thereby obtained, particularly for the case of current surges, an important characteristic for power switchgear such as high-voltage power circuit breakers.

a assures In the invention, the grooved cone can also be simulated by two ring-shaped members spaced on a common axis by an elastic or resilient intermediate member which joins with each other these two conducting parts which separately engage the conducting rods in such a manner that a slight mobility between these parts is provided. The resilient intermediate member that, even with larger manufacturing tolerances or in the event of dimensional changes caused by wear during operation, the contact roller means thereby formed rests against each of the conducting rods at two points.

The first embodiment (FIG. 2) discussed in detail below has as a relief or groove in the conical surface of each contact roller. This groove may have an approximately circular profile. However, it is essential that the radius of curvature of the groove be less than the radius of curvature of the contact rod, so that two contact points are provided between each contact rod and roller, as desired.

With a completely rigid contact roller means, two contact points at both contact rods cannot always be achieved because of the unavoidable tolerances with respect to the contact engagement force and the mobility of the contact roller means. However, in a contact roller means constructed in accordance with the invention, which connects two contact rods, at least three of the four contact points are always made, as compared to the maximum of two contact points made by conventional conical contact rollers. Thus, there is obtained in first approximation an increase of the current-carrying capacity by about 50 percent, as far as the limitation of the carrying capacity dictated by temperature rise is concerned.

The invention can also be realized advantageously by a symmetrical arrangement of two identical contact roller means with the surfaces having the grooves therein facing each other.

For a fuller explanation of the invention, two examples of embodiments are compared with a known contact device. The contact rollers here described may be part of a power circuit breaker in a high voltage system, with a movable conducting or contact pin represented in the drawings by one contact rod from which the current is to be conducted to another stationary contact rod.

The known contact apparatus shown in FIG. 1 consists of a stationary conducting or contact rod 10 and a movable conducting or contact rod 10, which may be for example the conducting contact pins of a highvoltage circuit breaker. A pair 4 of electrically conducting contact roller means serves for electrically connecting the pair of cylindrical conducting rods 10, 10, which have the same diameter and are arranged with their axes parallel. The pair 4 of contact roller means comprises two identical conical contact rollers 5 and 6 which are mounted on a shaft means 7 and are pressed against the conducting rods 10, 10', by means of a helical compression spring 8. A washer 11 is placed on the side facing away from a shoulder 10 on the shaft means 7, to serve as a stop for the spring 8. The washer I1 is held on the shaft means 7 by a cotter pin 12.

The conical exterior surfaces 15, 16 of contact rollers 5, 6, which are made of copper engage the conducting rods 10, 11' at points 15a, 15b, 16a, 16b. An individual contact roller is therefore electrically connected with the conducting rods only at two contact points, which are electrically in series.

An example of one embodiment of the instant invention is shown in FIG. 2, where the same reference numerals are used to identify elements first described with respect of FIG. 1.

In this embodiment, peripheral grooves 20, 21 are formed in the conical surfaces 15, 16 of the pair 4 of roller means 5, 6. The profile of each groove is substantially a circular arc 23 whose radius of curvature is less than that of the cylindrical conducting rods 10, 10. As a result of this construction, two parallel contact edges 24, 25, 26, 27, which comprise first and second portions of the respective roller means 5, 6 for making electrical contact with the conducting rods,

are formed effectively doubling the current transfer points through the roller means from one rod 10 to the other 10. The roller means 5 and the conducting rods 10, 10 always touch at two points 15a and 15a, and 15b and 15b, respectively. Similarly, roller means 6 and the rods l0, l touch at points 16a, 16a and 16b, 16b,

If the apparatus construction according to FIG. 2 is imprecisely assembled during manufacture or dislocated during use by wear or the like, from the position shown, it may happen that between roller means 5, 6 and the two conducting rods 10, 10, only three contact points are formed, of which two are connected in series with a single one. However, even in this case, an increase of approximately 50 percent of the electrical conducting capacity, as determined by the heat developed by continuous current, is obtained.

A second embodiment of the instant invention is shown in FIG. 3, where the same reference numerals are used to identify apparatus components described with reference to FIGS. 1 and 2. In this embodiment, roller means 5, 6 comprise ring members 15d, 15e and 16d, 16e which have a common axis and are axially mounted on shaft means 7. Elastic or resilient spacing conductor members 25, 26 are positioned respectively between ring members 15d, 15e and 16d, l6e on the shaft means 7. The radii of ring members 15d, 16d are greater respectively than the radii of ring members le,

l6e. Accordingly, the outer surfaces of ring members 15d, 152 and 16d, l6e comprise first and second portions of the respective roller means 5, 6 for making electrical contact with the conducting rods 10, The resilient members 25, 26 assure that the ring members d, 15e, 16d, l6e, respectively, of the roller means 5, 6 reliably make positive contact with two conducting rods 10, 10', under the action of the spring 8.

Although the invention has been illustrated with examples of embodiments incorporating cylindrical conducting rods of equal diameter and identical contact roller means in a symmetrical arrangement, it will be apparent to those of skill in the art that the principles of the invention can also be applied if the conducting rods have different diameters, or diameters that vary along their length.

What is claimed is:

1. Electrical contact apparatus comprising:

a parallel pair of electrical conducting rods of cylindrical cross-section capable of undergoing relative movement with respect to each other;

shaft means oriented between said rods;

first and second conical roller means axially mounted on said shaft means, each of said roller means having a peripheral groove spaced from the base thereof, said groove having a radius of curvature less than the radius of curvature of said rods, each edge of said groove engaging the surfaces of said rods to establish an electrical connection therewith; and

spring loaded means for positively holding said roller means against said rods.

2. Electrical contact apparatus comprising:

a parallel pair of electrical conducting rods of cylindrical cross-section capable of undergoing relative movement with respect to each other;

shaft means oriented between said rods;

first and second roller means axially mounted on said shaft means, each of said roller means comprising a pair of ring members and an elastic spacing member therebetween, the outer surface of each of said ring members engaging the surfaces of said rods to establish an electrical connection therewith; and

spring loaded means for positively holding said roller means against said rods.

3. A high voltage circuit breaker of the kind including at least one stationary electrical conducting pin and at least one movable electrical conducting pin spaced therefrom, wherein the improvement comprises:

shaft means oriented between said pins;

first and second conical roller means axially mounted on said shaft means, each of said roller means having a peripheral groove spaced from the base thereof, with a radius of curvature less than the radius of curvature of said pins, each edge of said groove engaging the surfaces of said pins to establish an electrical connection therewith; and

spring loaded means for positively holding said roller means against said pins.

4. A high voltage circuit breaker of the kind including at least one stationary electrical conducting pin and at least one movable electrical conducting pin spaced therefrom, wherein the improvement comprises:

shaft means oriented between said pins;

first and second roller means axially mounted on said shaft means, each of said roller means comprising a pair of ring members and an elastic spacing member therebetween, the outer surface of each of said ring members engaging the surfaces of said pins to establish an electrical connection therewith; and

spring loaded means for positively holding said roller means against said pins.

5. An electrical contact arrangement for transferring electrical energy between a pair of mutually parallel contact rods of an electrical switching apparatus such as a high-voltage circuit breaker or the like, the contact rods being capable of undergoing movement with respect to each other, the arrangement comprising at least one cone-shaped member for making contact with each of the rods; groove means formed in the conical surface of said cone-shaped member to define at least two mutually parallel edges in said surface for making electrical contact with each of the rods; and spring means for spring loading said cone-shaped member in a direction to hold the same in contact with each of the rods at said edges thereby providing at least two energy transfer points between each one of the rods and said cone-shaped member.

6. The electrical contact arrangement of claim 5 for transferring electrical energy between a pair of mutually parallel contact rods each having a rounded crosssection, said groove means being a rounded groove having a curvature greater than the curvature of the contact rods.

7. The electrical contact arrangement of claim 5 comprising an additional cone-shaped member for making electrical contact with the contact rods; said additional cone-shaped member having a configuration corresponding to the configuration of said firstmentioned cone-shaped member; said cone-shaped members being arranged symmetrically with respect to the contact rods in a manner to cause the groove means of said first-mentioned coneshaped member to be mutually adjacent the groove means of said additional cone-shaped member; and said spring means including means for also spring loading said additional cone-shaped member in the direction to hold the same in contact with each of the contact rods at the edges defined by said groove means thereof.

8. An electrical contact arrangement for transferring electrical energy between a pair of mutually parallel contact rods of an electrical switching apparatus such as a high-voltage circuit breaker or the like, the contact rods being capable of undergoing movement with respect to each other, the arrangement comprising at least one pair of ring-shaped members spaced from each other and having a common axis, one of said ring-shaped members having a radius different than the radius of the other one of said members, said ringshaped members having respective surfaces for making electrical contact with the contact rods; spring means for spring loading said pair of ring-shaped members in a direction to hold the same in contact with the contact rods at said outer surfaces of said members; and, an

' elastic spacer disposed between said ring-shaped memfrom one contact rod to the other. 

1. Electrical contact apparatus comprising: a parallel pair of electrical conducting rods of cylindrical cross-section capable of undergoing relative movement with respect to each other; shaft means oriented between said rods; first and second conical roller means axially mounted on said shaft means, each of said roller means having a peripheral groove spaced from the base thereof, said groove having a radius of curvature less than the radius of curvature of said rods, each edge of said groove engaging the surfaces of said rods to establish an electrical connection therewith; and spring loaded means for positively holding said roller means against said rods.
 2. Electrical contact apparatus comprising: a parallel pair of electrical conducting rods of cylindrical cross-section capable of undergoing relative movement with respect to each other; shaft means oriented between said rods; first and second roller means axially mounted on said shaft means, each of said roller means comprising a pair of ring members and an elastic spacing member therebetween, the outer surface of each of said ring members engaging the surfaces of said rods to establish an electrical connection therewith; and spring loAded means for positively holding said roller means against said rods.
 3. A high voltage circuit breaker of the kind including at least one stationary electrical conducting pin and at least one movable electrical conducting pin spaced therefrom, wherein the improvement comprises: shaft means oriented between said pins; first and second conical roller means axially mounted on said shaft means, each of said roller means having a peripheral groove spaced from the base thereof, with a radius of curvature less than the radius of curvature of said pins, each edge of said groove engaging the surfaces of said pins to establish an electrical connection therewith; and spring loaded means for positively holding said roller means against said pins.
 4. A high voltage circuit breaker of the kind including at least one stationary electrical conducting pin and at least one movable electrical conducting pin spaced therefrom, wherein the improvement comprises: shaft means oriented between said pins; first and second roller means axially mounted on said shaft means, each of said roller means comprising a pair of ring members and an elastic spacing member therebetween, the outer surface of each of said ring members engaging the surfaces of said pins to establish an electrical connection therewith; and spring loaded means for positively holding said roller means against said pins.
 5. An electrical contact arrangement for transferring electrical energy between a pair of mutually parallel contact rods of an electrical switching apparatus such as a high-voltage circuit breaker or the like, the contact rods being capable of undergoing movement with respect to each other, the arrangement comprising at least one cone-shaped member for making contact with each of the rods; groove means formed in the conical surface of said cone-shaped member to define at least two mutually parallel edges in said surface for making electrical contact with each of the rods; and spring means for spring loading said cone-shaped member in a direction to hold the same in contact with each of the rods at said edges thereby providing at least two energy transfer points between each one of the rods and said cone-shaped member.
 6. The electrical contact arrangement of claim 5 for transferring electrical energy between a pair of mutually parallel contact rods each having a rounded cross-section, said groove means being a rounded groove having a curvature greater than the curvature of the contact rods.
 7. The electrical contact arrangement of claim 5 comprising an additional cone-shaped member for making electrical contact with the contact rods; said additional cone-shaped member having a configuration corresponding to the configuration of said first-mentioned cone-shaped member; said cone-shaped members being arranged symmetrically with respect to the contact rods in a manner to cause the groove means of said first-mentioned coneshaped member to be mutually adjacent the groove means of said additional cone-shaped member; and said spring means including means for also spring loading said additional cone-shaped member in the direction to hold the same in contact with each of the contact rods at the edges defined by said groove means thereof.
 8. An electrical contact arrangement for transferring electrical energy between a pair of mutually parallel contact rods of an electrical switching apparatus such as a high-voltage circuit breaker or the like, the contact rods being capable of undergoing movement with respect to each other, the arrangement comprising at least one pair of ring-shaped members spaced from each other and having a common axis, one of said ring-shaped members having a radius different than the radius of the other one of said members, said ring-shaped members having respective surfaces for making electrical contact with the contact rods; spring means for spring loading said pair of ring-shaped members in a direction to hold the same in contact with the contact rodS at said outer surfaces of said members; and, an elastic spacer disposed between said ring-shaped members for maintaining the mutual spacing thereof and for coacting with said spring means to ensure the reliable contact of said ring-shaped members with the contact rods whereby each of said ring-shaped members defines an electrical path between the contact rods across which the electrical energy is transferrable from one contact rod to the other. 